Balancing device, dialysis machine, extracorporeal circulation and method for balancing fluids with a fluid measuring cell

Abstract

A balancing method and a balancing device ( 100, 101, 200, 201, 301, 303 ) for determining a fluid balance between a flow quantity in a first flow path (FW 1 ) and a flow quantity in a second flow path (FW 2 ) are disclosed. The disclosed balancing device ( 100, 101, 200, 201, 301, 303 ) comprises the following elements: a differential flow measuring unit (D) for measuring the differential flow between a flow in the first flow path (FW 1 ) and a flow in the second flow path (FW 2 ), a branch from one of the two flow paths (FW 1 , FW 2 ) for diverting fluid from one of the two flow paths into the other flow path (W), a device for setting the flow quantity (P 11 , P 12 ) in the additional flow path, which can be controlled in such a way that the measured differential flow fulfills a predetermined condition, and with a device (K) for determining the flow quantity in the additional flow path as a measure of the fluid balance.

1 . A balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) for determining a fluid balance between a flow quantity in a first flow path (FW 1 ) and a flow quantity in a second flow path (FW 2 ), comprising
 a differential flow measuring unit (D) for measuring the differential flow between a flow in the first flow path (FW 1 ) and a flow in the second flow path (FW 2 ),   a branch from one of the two flow paths (FW 1 , FW 2 ) for diverting fluid from one of the two flow paths into the other flow path (W),   a device for setting the flow quantity (P 1 , P 2 , P 4 , P 11 , P 12 ) in one of the two flow paths and/or in the additional flow path, which can be controlled in such a way that the measured differential flow fulfills a predetermined condition,   and with a device (K) for determining the flow quantity in the additional flow path as a measure of the fluid balance.   
     
     
         2 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the device for setting the flow quantity (P 11 , P 12 ) in the additional flow path (W) includes the device for determining the flow quantity in the additional flow path (P 11 , P 12 ). 
     
     
         3 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the device for setting the flow quantity (P 1 , P 2 , P 4 , P 11 , P 12 ) in one of the two flow paths and/or in the other flow path is designed as an adjustable pump (P 11 , P 12 ). 
     
     
         4 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the differential flow measuring unit (D) is designed as a differential flow sensor for direct measurement of the differential flow between the flow in the first flow path and the flow in the second flow path without a separate measurement of the flow in the first flow path or a separate measurement of the flow in the second flow path. 
     
     
         5 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 4 , wherein the differential flow sensor has a first flow measuring cell (K 1 ) in the first flow path (FW 1 ) and a second flow measuring cell (K 2 ) in the second flow path (FW 2 ), in the second flow path (FW 2 ), the flow passing through the flow measuring cell in countercurrent with the first flow measuring cell. 
     
     
         6 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the differential flow measuring unit comprises a first flow sensor K 1  for measuring the flow in the first flow path and a second flow sensor K 2  for measuring the flow in the second flow path. 
     
     
         7 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 6 , wherein the first and/or the second flow sensor is a flow measuring cell designed as a volume flow sensor or a mass flow sensor. 
     
     
         8 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the additional flow path has a cutoff valve. 
     
     
         9 . The balancing device ( 100 ,  101 ,  200 ,  201 ,  301 ,  303 ) according to  claim 1 , wherein the predetermined condition is satisfied when the differential flow is approximately zero. 
     
     
         10 . The balancing device ( 100 ,  101 ) according to  claim 1 , wherein the device for determining the flow quantity in the additional flow path comprises a container for collecting the flow quantity, and the flow quantity can be determined gravimetrically or by filling level detection. 
     
     
         11 . The balancing device according to  claim 10 , wherein the container is a bag. 
     
     
         12 . The balancing device ( 200 ,  201 ,  301 ) according to  claim 1 , wherein the additional flow path W upstream or downstream from the differential flow sensor D opens back into one of the two flow paths upstream or downstream and thereby forms a parallel flow path to one of the two flow paths. 
     
     
         13 . The balancing device according to  claim 1 , wherein the differential flow is determined as a flow rate or as a flow volume. 
     
     
         14 . The balancing device according to  claim 1 , partially or completely embodied as a disposable article or as part of a disposable article. 
     
     
         15 . The balancing device according to  claim 1 , wherein the differential flow can be measured as a differential volume, as an integral of a differential flow or as the difference between an integral of the flow in the first flow path and an integral of the flow in the second flow path. 
     
     
         16 . A dialysis machine comprising a balancing device according to  claim 1  for balancing dialysis fluid. 
     
     
         17 . An extracorporeal blood treatment unit having a blood path and a dialysis fluid path containing a balancing device according to  claim 1  for balancing dialysis fluid in the dialysis fluid path. 
     
     
         18 . A method ( 500 ,  600 ) for determining a fluid balance between a flow quantity in a first flow path and a flow quantity in a second flow path, having a balancing device according to  claim 1 , wherein the method comprises the following steps:
 measuring a differential flow between a flow in the first flow path and a flow in the second flow path (S 1 , S 62 ),   using the measured differential flow as a manipulated variable for the device for setting the flow quantity in the additional flow path (S 2 , S 63 ) and   determining the flow rate in the additional flow path as a measure of the fluid balance (S 3 ).   
     
     
         19 . The method according to  claim 18 , wherein the predetermined condition is met when the differential flow is approximately zero.